This thesis presents the results of a spectropolarimetric survey aimed at detecting directly the presence of magnetic fields in Wolf-Rayet (WR) stars. The search for the elusive WR fields began by observing the highly variable WN4 star EZ CMa = WR6 = HD 50896 and continued among a sample of eleven bright WR stars. All observations were obtained using the highly-efficient ESPaDOnS spectropolarimeter at the Canada-France-Hawaii telescope. The methodology used in this study attempts to detect the characteristic circular polarization (Stokes V) pattern in strong emission lines that is expected to arise as a consequence of a global magnetic field with a split monopole configuration. Since Stokes V data were affected by significant cross-talk from linear polarization to circular polarization, the spurious cross-talk signal was removed prior to applying the magnetic analysis. In the end, no magnetic fields are unambiguously detected in any of the observed stars. Nonetheless, the data show evidence supporting marginal detections for WR134, WR137 and WR138 for which the most probable field intensities, in the observable parts of the stellar winds, are B ~ 200, 130 and 80 G, respectively. In the case of non-detections, the average field strength upper-limit for the magnetic field is B ~ 500 G. Finally, this study cannot confirm the magnetic origin of co-rotating interaction regions observed in several WR stars since, out of 4 stars showing CIR-type variability, none showed decisive evidence for the presence of magnetic fields.